Enabling GZip compression on Plesk 11.5’s nginx

One of the legacy systems we still use at Flosoft.biz is Plesk. Over the last few years it has slowly gotten better (don’t worry, it still completely breaks on every version upgrade) and nowadays comes with nginx.

However, I noticed that for some obscure reason, it doesn’t enable GZip compression for the webpages it serves? This is quite odd, having myself worked a lot with nginx over the last few years, it’s a default configuration!